Construction of gas-or vapor-filled discharge vessels



fan, Is 1941- M. STEENBECK 3 5 CONSTRUCTION OF GAS- OR VAPOR-FILLED DISCHARGE VESSELs Filed Aug. 6, 1958 5 sheets -sheet l iNVENTOR i /4): 5 .YLGE/VZMC/Y Jan. 1941. M. STEENBECK CONSTRUCTION OF GAS- OR VAPOR-FILLED DISCHARGE VESSELS Filed Aug. 6, 1938 5 Sheets-Sheet 2 fig a Jan. 7, 1941. M. STEENBEZCK CONSTRUCTION OF GAS- 0R VAPOR-FILLED DISCHARGE VESSELS 3 Sheets-sheaf, 5

Filed Aug. 6, .1938

INVENTOR Max fifeenbeck BY W Patented Jan. 7 1941 CONSTRUCTION 01! GAS- R VAPOR-FILLED DISCHARGE YESSELS Max Steenbeck, Berlin-Siemensstadt, Germany, assignor to Patentverwertungs- Gcsellschait mit beschrinkter Haitung "Hermes," Berlin, Germany, a corporation of Germany I Application August 8, 1938, Serial No. 223,541

In Germany August '1, 1937 8 Claims.

The present invention relates to the construction of gasor vapor-filled discharge vessels for high operating voltages in which a discharge passes between an electron emitting source and tively charged and no matter whether they trav in a direction towards the anode or towards the cathode of the discharge vessel-and impinge upon metallic surfaces of the intermediate electrodes.

s one or more anodes and which may be used to In this manner they are prevented from reaching 6 control or convert high-voltage currents. The the discharge path and are rendered innocuous. purpose of such discharge tubes is to prevent back- Instead of the honeycomb-like part also various fires with certainty despite the high operating concentrical cylinders may be employed. voltage. To this end it has already been proposed In the case of the rotation symmetrical interw to efl'ectauniiorm distribution of the voltage along mediate electrodes as shown this effect is not 10 the discharge path by means of intermediate elecutilized to its full extent as regards the ions and trodes lying between the electron emitting source electrons travelling along the axis of rotation. To and the anode. However, this means is not sufrender innocuous also these ions and electrons ilcient to ensure a proper operation at high operthey may be directed into a hollow space of the i6 ating voltages, According to the invention the anode which is substantially free of lines of force intermediate electrodes are so designed that the so that the electrons released by the particles imlines of force running between the electrodes folpinging upon the electrodes cannotsubstantially lowing one another are substantially inclined to cause an ionization of the discharge path. the discharge path and deviate the ions or elec- Another method consists in the fact that the go trons present in the discharge space towards concentrally travelling ions or electrons are directed ducting parts. It is particularly advantageous to towards intercepting surfaces of the intermediate design the electrode in such a manner that electrodes. To this end, iorinstance, the central a plurality of channels result whose dimensions tube of the tubes 3 (Fig. 2) may be closed by a are relatively small in. the direction perpendicular metal disk. It is preferable to arrange this metal to the discharge path. The ions or electrons disk in the middle of the tube as shown in Fig. 1. 25 which are deviated in either direction impinge The intercepting surface in this figure is denoted upon a metallic part after having travelled a by the numeral 5. By this arrangement the interrelatively short distance. It is advisable to make cepting surface is arranged in a space substanthe length of the single chambers of the part, tially free of lines of force so that also there the so for instance, in the form of a honeycomb equal electrons released by the-impinging ions or electo or greater than the width thereof. trons do not cause any disturbances.

In Figs. 1 and 2 of the accompanying drawings To prevent the centrally flying particles from is shown a pair of such electrode systems. They impinging upon the emissive parts of the cathode consist of a honeycomb-like part I which is comit is preferable to arrange in front of the cathode as posed of a cylindric tube 2 of a comparatively .a hollow body whose opening is directed towards as large diameter (Fig. 2) and of various smaller the cathode and into which body pass the ions or tubes 3 surrounded by the tube 2. Integral with electrons flying towards the cathode. A cathode the honeycomb-like part I is a cylindrical part 4 thus protected is shown in Fig. 3. 20 is an indiof greater diameter which encloses the honeyrectly heated hollow cathode surrounded by the 0 comb-like part of the next following electrode metallic sleeve 2|. In this sleeveissuspended the a; system. The central zone of the honeycombcapsule 22, for instance, by means of a perforated like part extends into the preceding electr'ode. sheet. In the cylinder 2| may also be arranged a In this manner a field distribution is attained honeycomb-like part and the end of the central which is similar to that which would result chamber facing the cathode may be closed. 23

5 between two adjacent spherical shells. By flner is an intermediate cathode designed as shown in subdivisions of the honeycomb-like part and suit- Fig. 1. able grading of the individual zones a field dis- Fig. 4 shows a discharge vessel according to the tribution may be brought about which is very siminvention. 6, l, I, 9, i0 and II are intermediate ilar to the field distribution between the two electrodes which are designed in the manner as spherical shells. The field distribution is indishown in'Figs. l and 2. His the anode which is 50 cated by the dotted lines lying between the elecprovided inside with a bulb-shaped recess ll, into trodes. By the lines of force running between whichpass the centrally flying ions or electrons. the adjacent electrodes and which are inclined to 5 By suitably designing the anode I! the lines of the discharge path, particles are deviated-reforce between this anode and the adjacent inters gardless of whether they are positively or negamediate electrode ll may be caused to run in a I similar manner as between the intermediate electrodes so that the same conditions are present also in the last step of the tube. M denotes the cathode. In this case it is assumed that a hollow cathode is employed in which alkaline earth metal oxides are used as electron emitting substances. Instead of a hot cathode also an auxiliary discharge, particularly an auxiliary arc, in Hg-vapor may be employed. In this case it is advisable to cause in the neighborhood of the cathode a condensation of the metal vapor developed, suitable cooling arrangements being provided for this purpose. In front of the cathode is arranged the control electrode I! which is designed in a similar manner as the lower part of the intermediate electrodes (Fig. 2). Below the control electrode are arranged two metal cylinders, one of which (l6) encloses the cathode, the leads and under circumstances the squash. The upper part of the control electrode is secured to a cylindrical extension of a large diameter which encloses the honeycomb-like part of the intermediate electrode 6. Also the lines of force between the intermediate electrode 6 and the control electrode l5 inclusive of the cylindrical part [1 run substantially in the same manner as the lines of force between the intermediate electrodes. The discharge vessel may be filled up with mercury vapor, inert gases or with a mixture of inert gases and metal vapors. As will be seen from Fig. 4 the edges of the single electrodes are rounded off in order to avoid too high fleld densities at some points of the electrode.

In the embodiment shown in Fig. 4 the honeycomb-like parts of the intermediate electrode are directed towards the cathode. However, also an inverted construction may be employed, since the ions or electrons flying into the discharge space are deviated towards metallic surfaces irrespective of the polarity or the direction of travel thereof.

The above considerations as to the behavior of load vehicles in the discharge space are only applicable if the discharge has not yet been ignited. As soon as the discharge ignites, i. e., for instance, in the direction of flow in the case of a rectifier operation or if the discharge has been initiated with the aid of the control grid in the case of a controlled discharge vessel the discharge is not appreciably influenced by the intermediate electrodes so that the discharge may burn without hindrance.

In the device according to Fig. 4 it has been assumed that the central portion of the intermediate electrodes 6 to H is provided with intercepting surfaces according to Fig. 1 (as indicated by 5). As above mentioned it is sufficient to provide the inside of the anode with a recess. This applies particularly to cases where the impinging point of the stream of ions lies as deep as possible in the anode, so that the greatestpart of the neutral and charged particles issuing from the impinging point impinge upon the walls of the recess and do not therefore pass into the discharge space proper. The material at the impinging point of the stream of ions is preferably of such a nature that it disintegrates to the smallest possible extent and emits a small amount of secondary electrons. Such a material may also be inserted in an electrode consisting of another material in a similar manner as is performed in the case of anticathodes of X-ray tubes provided with tungsten sheets.

The electric fields prevailing between the intermediate electrodes are naturally only eflective if a suitable voltage is applied to the electrodes during the periods for which no discharge is desired. In view of the disruptive strength 01' the discharge vessel voltages lying between the anode and cathode potential are supplied according to the invention to the intermediate electrodes, for instance, with the aid of a capacitive potentiometer. When dimensioning this potentiometer care should be taken to bring about an approximately uniform voltage distribution owing to the different distribution of the capacity (capacities to earth and the capacities of the electrodes with respect to one another). Such a capacitive potentiometer is shown schematically in Fig. 5. For the sake of simplicity also the intermediate electrodes are schematically shown. 2'! denotes the hot cathode, 28 the heating battery and 24 the current consuming device. The energy is supplied by an alternatingcurrent source 28 and is transmitted by a transformer 25 to the circuit including the current consuming device. In general it will be necessary to cause a decrease of the value of the capacities of the potentiometer from the anode in the direction towards the cathode, since the self-capacity of the electrodes of the discharge vessel varies in the opposite direction. It is also possible to employ the self-capacities of the electrodes for dividing the voltage. However, this method can only be employed in particular cases and only if the construction of the tube permits a sufliciently accurate adjustment of the capacity values between the electrodes.

It has been found advantageous to choose the differences of potential between the anode and the next following intermediate electrode and between the grid and the adjacent intermediate electrode somewhat smaller than the differences of potential between the other electrodes. To this end care must be taken to see that the capacities anode-intermediate electrode and gridintermediate electrode respectively are greater than the capacities between the intermediate electrodes. The reason for the increased disruptive strength of an arrangement thus dimensioned lies apparently in the fact that the voltage surges occurring during the switching operations make themselves particularly felt at the ends of the discharge vessel.

In the tube above-described it has been assumed that an electron emitting source always ready for operation is present in the form of a hot cathode or of an auxiliary discharge. The increased disruptive strength of the tube may, however, be utilized according to the invention if the auxiliary discharge is only initiated for igniting the vessel. (Ignitron) As above pointed out the projecting parts of the intermediate electrodes may be either directed towards the cathode or towards the anode, since the ions or electrons are deviated under all circumstances towards metallic parts. However, the results in both cases are not exactly the same. Undesirable discharges are avoided with greater certainty if the projecting parts of the intermediate electrodes are directed towards the electrode which is positive in the moment under consideration. In the embodiment shown in Fig. 2 an undesirable discharge is therefore avoided with greater certainty during the inverse phase. This depends upon the fact that the electrons released by the positive ions at the intermediate electrodes are directed back to the intermediate electrodes, whereas in case the current flowing in the opposite direction they impinge upon the next intermediate electrode and may ioniae on their way to the latter and release further electrons at the electrode itself. Therefore, the in- 5 termediate electrodes will be arranged in such a direction as to attain the greatest'protection against undesirable discharges for the conditions of operation of particularly long duration. In the case of a rectifier, particularly of the multi-phase type, connected to a counter-voltage this applies to the inverse phase. The-intermediate electrodes will therefore be arranged in the direction shown in Fig. 2. Under circumstances the same conditions may be obtained for both directions of current by the fact that intermediate electrodes are arranged in an alternative sense. For the same purpose also symmetric lntermediate electrodes may also be employed which may be obtained if corresponding sides of two of the intermediate electrodes shown in Fig. 1 are connected.

The arrangement of the intermediate electrodes according to the invention entails the lateral bringing out of the leads for the individual electrodes, since the tubes have a rather. great length. The dissipation of heat through the current supply leads is relatively great so that the degassing of the electrodes is hardly possiblewith the aid of high frequency and it may easily happen that the seals get damaged. The construction shown in Figs. 8 and 7 is therefore employed to advantage, which differs from that shown in Fig. 4 in that the electrodes are secured .in a particular manner. The intermediate electrodes and under circumstances also the control grids are secured in a supporting tube of quartz or a ceramic material.

This supporting tube is placed after mounting the electrodes in the discharge vessel proper and is there held in the desired position. In this case there remains a small distance between the discharge vessel and the supporting tube and the intermediate electrodes respectively, so that when de-gassing the electrodes there is no fear of damaging the wall of the vessel. Furthermore,

by designing the holding members for the intermediate electrodes in a suitable manner only small amounts of heat are transferred to the supporting tube.

Such an embodiment of the invention is shown in Fig. 6; 3| denotes the wall of the discharge vessel, 32 is a cathode. It is assumed that in this case an indirectly heated hollow cathode is employed. Instead of such a cathode also an auxiliary discharge, for instance, an auxiliary arc in mercury vapor may be employed which is arranged in this case preferably laterally of the anode tubes. The supporting tube consisting, for

instance, of quartz is denoted by the numeral 62. The anode 33, the intermediate electrodes 34, 35

and under circumstances other intermediate electrodes of the same or similar construction (not shown) are secured within this tube. Furthermore, the two grids 36 and 31 are arranged in the supporting tube. These grids may serve a variety of purposes, for instance, for control purposes orto check ions or electrons. The lower end of the grid 31 is provided with a cylindrical extension surrounding the cathode and ending in a holding device for the supporting tube.

The intermediate electrodes and the grids are preferably secured in such a manner that these electrodes are surrounded by a U-shaped ring 33 as shown in Fig. '7. This ring has a somewhat 73 smaller diameter than the supporting tube '2 so as to prevent an immediate transfer of heat between these parts. The screw 33 lying in bores of the supporting tube is screwed into this ring. One of these screws may be provided with a current supp-1y wire for the intermediate electrodes. 5 It is preferable to determine the position of the electrodes with respect to the supporting tube by resilient fingers in such a manner that the heat carried oil by the electrodes will not deteriorate the supporting tube. 10

The intermediate electrodes consist of a plurality of tube sections of diiferent diameter lying within one another and which are displaced in axial direction with respect to each other for the purpose of forming a ileld of a suitable conflgura- 15 tion. The central cylinders are besides closed by intermediate walls 40 which serve to check the flying ions or electrons. In the upper end of the supporting tube (Fig. 1) is secured besides the anode 33 a metal shield 49 surrounding the anode. 20 The edges of this shield are also rounded off in the same manner as those of the intermediate electrodes and grids. The central portion of the shield is provided with an extension 4| engaging in a groove of the anode. In this manner rapidly 25 flying ions or electrons are prevented from flying in the outward direction and from charging the supporting tube or the wall of the vessel. The supporting tube is held in position at the upper end thereof by means of the ring-shaped cap 42 held in position by a groove 43 arranged in the supporting tube with the aid of the ring 44. The cap ends in a tubular portion 45 which surrounds the upper squash of the discharge vessel. In this manner the radial position of the supporting tube 35 as well as of the intermediate electrodes is determined. The axial position is determined with the aid of the resilient (slotted) ring 40 which on the onehand is secured in the tube 43 and on the other hand is insulatedly arranged with respect to the anode current supply rod 41. The resilient rings 46 can take up tensile or compressive forces but they are elastic transversely to the axis of the current bushing and prevent in this manner relatively great lateral forces from being transmitted 45 to the current bushing. A device of a similar or of the same type for preventing axial displacements may also be provided for the cathode bushings. The two insulating rings 48 serve to insulate. The insulation is necessary at this point if 50 the screen 49 is not to be directly connected with the anode. It is advisable to insert a resistance between the anode and this screen in order to prevent the screen from conducting current. The current supply to this screen is denoted by the numeral 50. The supporting tube is held in position at the lower end thereof by the U-shaped ring 5| which is integral with a cylindrical sleeve 52 and secured to the lower tubular portion of the control grid 31. The sleeve 52 surrounds the lower m squash and prevents the lower end of the supporting tube from being displaced in the radial direction.

To prevent discharges along the inside wall of the discharge vessel it is preferable to arrange in the neighborhood of the current bushingsfor the intermediate electrodes, circular metallic coatings which are electrically connected to the current supplies and to the intermediate electrodes respectively. These metallic coatings may 70 be made so thin that the r electric resistance is so high that they are .not appreciably heated when the discharge vessel is operated with high frequency. By the use of thicker rings the current path may be interrupted by slots, thus preventing 7 an undesirable heating of these rings. These metallic coatings are denoted by the numeral 51. Exteriorly of the discharge vessel they may be surrounded with protective caps (not shown) which may be provided with rounded oi'f edges to prevent too high field densities (corona). 54 denotes an electrostatic screen surrounding the anode arrangement and which may be connected to the anode.

The type of the discharge vessel according to the invention permits to de-gas by high frequency all electrodes lying in the immediate neighborhood of the discharge and which are therefore heated in operation to a high temperature. So far as an immediate transfer of heat between the electrodes and the wall of the vessel is possible, for instance, in the neighborhood of the cathode the metallic parts are given such a length that the parts lying in the neighborhood of the seal are not appreciably heated in operation and therefore a de-gassing at a high temperature is not necessary.

To prevent the ions or electrons from impinging upon the wall of the vessel and from causing there disturbing discharges, the following provisions are preferably made:

The anode is covered with respect to the vessel wall by a conductive screen which has substantially the anode potential. This screen may be connected to the anode, for instance, through a high ohmic resistance of the order of magnitude of 10 ohm. In the gap between the anode and the above-mentioned screen engages a portion of the preceding intermediate electrode.

Fig. 8 is another embodimentof the invention, in which is shown only the upper part of the anode rm containing the anode. The anode arm may consist of glass but it may also be composed of a plurality of tube sections SI of ceramic material, for instance, in the manner that the metallized ends of the tubes are soldered to one another. 82 and 63 denote the series electrodes which are held in position by metallic rings lying between the single tube sections 6|. A voltage lying between the anode and cathode potential may be impressed on these tube sections, for instance, with the aid of a capacitive potentiometer. In this manner it diate electrodes which is characterized by the lines of force inclined to the axis of the tube. By such lines of force the ions or electrons are rapidly removed from the discharge path as long as the discharge is not yet ignited. The anode 68 is supported by the current supply bolt 69. HI is a metallic plate which closes the anode arm. The underside of the plate carries the calotteshaped part H consisting, for instance, or graphite facing the concave portion of the anode. This construction permits in a known manner to adjust the anode without there occurring any changes in the distance between the anode and the part I l. The cylindrical screen 12 surrounding the anode is secured to the part II. The plate 10 is conductively connected to the part H and the screen 12 and is insulated from the anode by the insulating body 13. Both parts may be connected to each other by means of the resistance H. Under circumstances the insulating body Il may be given a certain conductivity so that a particular resistor may be dispensed with. In the space between the anode 88 and the screen 12 extends the cylindric part 15 of the series electrode 13. Ions or electrons which impinge upon the anode can therefore only impinge upon the wall of the vessel after repeated reflection. It is hardly possible that the ions or electrons pass in the space outside the screen I! so that no detrimental discharges can be produced by the small quantity of ions or electrons entering this space. 16 is a spherical screen which prevents the corona phenomena on the outer parts of the anode construction.

What is claimed is:

l. A gasor vapor-filled discharge vessel comprising an electron emitting source, an anode and intermediate electrodes arranged between said anode and the electron emitting source, the intermediate electrodes being secured in a tube of quartz or ceramic material carrying the same and which is arranged in the discharge vessel.

2. A gasor vapor-filled discharge vessel comprising an electron emitting source, an anode and intermediate electrodes arranged between said anode and the electron emitting source, the intermediate electrodes being secured in a tube of quartz or ceramic material carrying the same and which is arranged in the discharge vessel, the intermediate electrodes being supported by springs with respect to the supporting tube.

3. A gasor vapor filled discharge vessel comprising an electron emitting source, an anode and intermediate electrodes arranged between said anode and the electron emitting source, the intermediate electrodes being secured in a tube of quartz or ceramic material carrying the same and which is arranged in the discharge vessel, the leads to the anode or cathode being connected to the supporting tube through resilient members so as to prevent lateral forces from being transmitted to the anode current supply leads.

4. A gasor vapor filled discharge vessel comprising an electron emitting source, an anode and intermediate electrodes arranged between said anode and the electron emitting source, the intermediate electrodes being secured in a tube of quartz or ceramic material carrying the same and which is arranged in the discharge vessel, the intermediate electrodes being surrounded by U-shaped rings'which close the space between the electrodes and the supporting tube.

5. A gasor vapor-filled discharge vessel comprising an electron emitting source, an anode and intermediate electrodes arranged between said anode and the electron emitting source, the anode being covered with respect to the discharge vessel wall by a conductive screen and a part of the intermediate electrode extending into the gap between the screen and the anode, said screen being secured to a metal cover plate of the anode arm and the anode supply lead being connected to said plate. i

6. In an electrical discharge vessel, an anode, a cathode, and a plurality of intermediate electrodes collectively forming walls about the discharge path therebetween, the ends adjacent the cathode oi individual intermediate electrodes telescoping into and extending within the adjacent intermediate electrode.

7. In an electrical discharge vessel, an anode, a cathode, anda plurality of intermediate electrodes collectively forming walls about the discharge path therebetween, the ends of individual intermediate electrodes telescoping into and extending within the adjacent intermediate electrode and having their cross-sections subdivided by longitudinally extending partitions.

8. In an electrical discharge vessel, an anode, a cathode, and a plurality of intermediate electrodes collectively forming walls about the discharge path therebetween, the ends of individual intermediate electrodes telescoping into and extending within the adjacent intermediate elec trode and having their cross-sections subdivided by longitudinally extending partitions, and means for impressing voltages intermediate between those or said anode and cathode on said intermediate electrodes, the potential difference between the anode and the adjacent intermediate electrode being less than that between adjacent intermediate electrodes, whereby the voltage distribution A during switching operations is more evenly distributedthereby protecting the ends of the discharge vessel from excessive voltage strains.

MAX STEENBFCK. 

